A pilot mental health service for troubled youths will open at Perth Children's Court next year.
In a WA first, mental health experts will be stationed at the court to provide assessments, referrals and treatment to young people to help divert them from crime.
Commissioner for Children and Young People Michelle Scott welcomed the service after her inquiry into the mental health and wellbeing of young people found there was a severe lack of mental health services for children in the criminal justice system.
"The Inspector for Custodial Services estimated that up to 50 per cent of young people in custody at any given time could be experiencing mental health issues," she said.
Ms Scott said WA lagged behind many other States in the provision of these services.
"Victoria, for example, has a dedicated Children's Court clinic that undertakes psychological and psychiatric assessments and some treatments of children and families to support court proceedings," she said.
Mental Health Minister Helen Morton said $1.7 million was allocated in the May Budget to pay for mental health experts to be placed at the court over two years.
Answers given to Labor MP Linda Savage in State Parliament show less than one per cent of the $773 million Department of Corrective Services budget is spent on mental health services.
In 2012-2013, $4.3 million will be directed to mental health services for adults while juvenile prisoners will get just $131,746, including $21,382 for a psychiatrist and $110,746 for a clinical nurse.
Shadow minister for corrective services Fran Logan said the scale of mental health problems in prisons was grossly underestimated.
"It is the general public who ultimately suffer from recidivist crimes carried out by those not properly diagnosed or treated while in custody," he said.
A spokesman said the Barnett Government did more in this year's Budget to help people with mental health issues than the Labor Party did during their entire previous term in government.